1. Name the two organs that make up the central nervous system.
Answer
Brain and spinal cord.
2. The eye is a sense organ containing two types of receptors. What are the receptors sensitive to ?
Answer
Light intensity and colour.
3. What is the difference between vasoconstriction and vasodilation ?
Answer
In vasoconstriction, blood vessels constrict (narrow), while in vasodilation, blood vessels dilate (widen).
4. Why does a person throw their arms out to the side as they begin to fall ?
Answer
The response is a reflex action that does not involve the conscious part of the brain.
5. The figure below shows the structure of the reflex arc that causes this response. Describe how the structures in a reflex arc cause the person's hand to move away from the sharp object.
Answer
The receptor detects the stimulus and generates an electrical impulse that passes along a sensory neurone towards the spinal cord. The impulse crosses a synapse to a relay neurone, and across another synapse to a motor neurone. The motor neurone transmits the impulse to a muscle (the effector) which contracts to bring about the response.
6. The brain is made of billions of interconnected cells. Name these cells.
Answer
These interconnected cells are called neurones.
7. Give one advantage and one disadvantage of using patients with brain damage to investigate brain function.
Answer
This allows scientists to find out more about the different parts of the brain and their functions. If the patient is brain damaged they may not be able to give consent to the procedure or the techniques could cause more damage to the patients' brains.
8. The student is reading a book and then looks up to read information the teacher has written on the board. Describe the changes that take place in the student's eye to allow them to focus on the distant object.
Answer
The ciliary muscles relax which increases their diameter and pulls the suspensory ligaments tight. The lens is then pulled thinner and refracts light rays less to focus the image on the retina.
9. Changes happen in a person's body when the thermoregulatory centre detects a rise in body temperature. Describe two changes that happen in the person's body.
Answer
Sweat is produced from the sweat glands and blood vessels dilate.